The present invention relates to solid state inertial rate sensors and particularly to a resonant beam or tuning fork rate sensor or gyroscope. The use of a homogeneous mass of material exhibiting piezoelectric properties, such as quartz, for sensing of inertial rate is known and several examples of its implementation are in the literature. Basically, such a rate sensor operates on the tuning fork principal of the Cariolis acceleration and utilizes the piezoelectric effect to induce tuning fork vibration in response to voltage applied to drive electrodes applied to each of the tuning fork tines to produce an enplane vibration and further operates by sensing the current generated by piezoelectric compression in the tines in vibrations out of the plane induced by inertial rate inputs.
Because the quartz material is electrostatically alive with field potentials due to the use of piezoelectrically induced vibrations such a quartz rate sensor tends to be a fairly noisy device owing to the presence of electrostatic fields throughout the quartz material which can interfere with the sensing electrodes and their electrical connectors and in addition, the sense circuits are electrostatically coupled to the drive voltage. In addition, the generation of an accurately controlled oscillation frequency and amplitude from an external oscillator requires expensive and precise compensation for the significant thermal effect on the quartz modulus of elasticity.